A person who is going to loose at a poke war...
Oh look it's Harby he can't win a poke war
A harby is a hobby that you like to do at Arby's.
It can be literally anything, as long as it's a hobby.
Person 1: "Cosplaying is my newest harby!"
Person 2: "Won't they kick you out?"
A Person: "Skydiving is one of the most dangerous harbies."
Another Person: "Yeah. And it's expensive. They always make you pay for the roof damage."